Here are several things you should know before using a web proxy.

Pros

• You don’t have to install anything
• Easy to use: just type in the desired URL and press Go/Submit
• There are plenty of proxies to choose from
• You can use secure proxies (https) to increase your privacy
• Best way to unblock sites (MySpace, Facebook, YouTube) from school, work or internet cafes
• There are paid versions that are more secured and faster (e.g. htpp://proxy.org)

 
Cons

• The IP addresses of web proxies are most of the time well-known and often blacklisted
• Streaming applications (like online radio or TV stations) are not supported. So you are not really able to watch YouTube videos
• Your personal information can be intercepted by the proxy owner (except for the https proxies)
• You are not able to choose the country or the location of the IP to be used
• Many proxies are full of ads, some of them being quite annoying (pop-ups, pop-unders, banners, etc)
• Most of the web proxies have a short life.

Source: How-To-Hide-IP.info

Happy Surfing!